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Re: [Qemu-devel] [PATCH v3 05/15] block/mirror: don't install backing ch
From: |
Max Reitz |
Subject: |
Re: [Qemu-devel] [PATCH v3 05/15] block/mirror: don't install backing chain on abort |
Date: |
Mon, 3 Sep 2018 11:24:46 +0200 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.9.1 |
On 2018-09-01 00:28, John Snow wrote:
> In cases where we abort the block/mirror job, there's no point in
> installing the new backing chain before we finish aborting.
>
> Move this to the "success" portion of mirror_exit.
>
> Signed-off-by: John Snow <address@hidden>
> ---
> block/mirror.c | 27 ++++++++++++++-------------
> 1 file changed, 14 insertions(+), 13 deletions(-)
>
> diff --git a/block/mirror.c b/block/mirror.c
> index cba555b4ef..c164fee883 100644
> --- a/block/mirror.c
> +++ b/block/mirror.c
> @@ -642,16 +642,6 @@ static void mirror_exit(Job *job)
> * required before it could become a backing file of target_bs. */
> bdrv_child_try_set_perm(mirror_top_bs->backing, 0, BLK_PERM_ALL,
> &error_abort);
> - if (s->backing_mode == MIRROR_SOURCE_BACKING_CHAIN) {
> - BlockDriverState *backing = s->is_none_mode ? src : s->base;
> - if (backing_bs(target_bs) != backing) {
> - bdrv_set_backing_hd(target_bs, backing, &local_err);
> - if (local_err) {
> - error_report_err(local_err);
> - ret = -EPERM;
> - }
> - }
> - }
>
> if (s->to_replace) {
> replace_aio_context = bdrv_get_aio_context(s->to_replace);
> @@ -659,9 +649,18 @@ static void mirror_exit(Job *job)
> }
>
> if (s->should_complete && ret == 0) {
> - BlockDriverState *to_replace = src;
> - if (s->to_replace) {
> - to_replace = s->to_replace;
> + BlockDriverState *to_replace = s->to_replace ? s->to_replace : src;
> +
> + if (s->backing_mode == MIRROR_SOURCE_BACKING_CHAIN) {
> + BlockDriverState *backing = s->is_none_mode ? src : s->base;
> + if (backing_bs(target_bs) != backing) {
> + bdrv_set_backing_hd(target_bs, backing, &local_err);
> + if (local_err) {
> + error_report_err(local_err);
> + ret = -EPERM;
> + goto clean;
> + }
> + }
> }
>
> if (bdrv_get_flags(target_bs) != bdrv_get_flags(to_replace)) {
Testing shows that on post-READY cancel, s->should_complete is 0 (which
makes sense, because all the rest in this path is about replacing
to_replace by target_bs, which we don't want to do on cancel), so this
would not be executed.
However, I think we do want to give the target the correct backing chain
when the job is canceled this way (as I suppose there are ways to keep
the target around even with drive-mirror).
So we should attach the backing chain whenever ret == 0, not just when
s->should_complete is true.
Max
> @@ -678,6 +677,8 @@ static void mirror_exit(Job *job)
> ret = -EPERM;
> }
> }
> +
> + clean:
> if (s->to_replace) {
> bdrv_op_unblock_all(s->to_replace, s->replace_blocker);
> error_free(s->replace_blocker);
>
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- Re: [Qemu-devel] [PATCH v3 05/15] block/mirror: don't install backing chain on abort,
Max Reitz <=